Switching Hearing Implant Coding Strategies

1. A computer based method implemented using at least one hardware implemented processor for generating electrode stimulation signals to electrode contacts in an implanted cochlear implant electrode array, the method comprising: using the at least one hardware implemented processor to perform the steps of: processing an input sound signal to generate a plurality of band pass signals, wherein each band pass signal represents a band pass channel defined by an associated range of audio frequencies, and wherein each band pass signal has a characteristic amplitude and temporal fine structure features; extracting band pass envelope signals reflecting time varying amplitude of the band pass signals; generating stimulation timing signals reflecting the temporal fine structure features of the band pass signals; monitoring a key feature value present in the input sound signal or the band pass signals; selecting from the plurality of band pass signals a subset of one or more selected band pass signals; for the one or more selected band pass signals and for a plurality of stimulation coding strategies, selecting a stimulation coding strategy based on the key feature value, wherein the plurality of stimulation coding strategies include: i. an envelope-based stimulation coding strategy based on the band pass envelope signals, and ii. an event-based stimulation coding strategy based on the stimulation timing signals; using the selected stimulation coding strategy to produce the electrode stimulation signals; delivering the electrode stimulation signals to the electrode contacts in the implanted cochlear implant electrode array; and switching between different selected stimulation coding strategies as a function of changes in the key feature value.

2. The method according to claim 1 , wherein switching between different selected stimulation coding strategies occurs directly without a transition period of time.

3. The method according to claim 1 , wherein switching between different selected stimulation coding strategies includes adaptively changing the selected stimulation coding strategy over a transition period of time to become a different stimulation coding strategy.

4. The method according to claim 3 , wherein the adaptively changing occurs after the key feature value changes from an initial value to a coding change value.

5. The method according to claim 3 , wherein the adaptively changing occurs while the key feature value changes from an initial value to a coding change value.

6. The method according to claim 1 , wherein one of the stimulation coding strategies uses adaptive stimulation pulse rates and another stimulation coding strategy uses constant stimulation rates.

7. The method according to claim 1 , wherein the key feature value is a signal to noise ratio (SNR) of the input sound signal.

8. The method according to claim 1 , wherein the key feature value is a direct to reverberation ratio (DRR) of the input sound signal.

9. The method according to claim 1 , wherein the key feature value is envelope slope of the band pass envelope signals.

10. The method according to claim 1 , wherein the key feature value is envelope peak of the band pass envelope signals.

11. The method according to claim 1 , wherein the key feature value is envelope amplitude of the band pass envelope signals.

12. The method according to claim 1 , wherein the one or more selected band pass signals is a single band pass signal.

13. The method according to claim 1 , wherein the one or more selected band pass signals is a plurality of selected band pass signals.

14. The method according to claim 13 , wherein an n of m strategy is used with the plurality of band pass signals.

15. The method according to claim 13 , wherein the plurality of selected band pass signals comprises a dominant channel having a largest key feature value and a plurality of adjacent channels.